Newly developed computer analyzed noninvasive techniques will be used in this study of physiological aging. Many different quantitative aspects of cardiac function measured by these techniques will be evaluated in a selected group of men and women 20-40 years of age. Sex differences in aging members of the group will be examined after effects due to body size and other sources of unwanted variability have been controlled. Effctiveness of the multiple objective physiological measurements of cardiac function as estimates of chronological age will be tested in data obtained. Healthy airline pilots, stewards, and stewardesses will undergo detailed medical evaluation before the special tests are given at the airline medical department (UA laboratory). High fidelity ballistocardiograms (Bcg) and percutaneous carotid arterial pulse recordings (CP) will then be obtained according to a new computer-oriented procedure developed by the applicant. The specially formatted analog tape recordings of these tests will subsequently be converted into digital tape format by an edit program in an institutional computer. These edited digital tapes will be analyzed by another program for feature recognition and detailed measurement of Bcq and CP in the same computer. Results of these analyses, along with clinical data on the subjects, will then be evaluated with the aid of standard biomedical statistical programs to elucidate aging trends which are expected in the data.